Quarry lake vs settling pond vs reservoir for floating solar
A developer who has screened a few dozen water bodies for floating PV already knows the pitch decks lie by omission. Every reservoir looks like a candidate on a map. Most aren't, once you check what the water level actually does over a year and whether the shoreline lets a crew get a barge in.
The three water body types that come up most in site selection, quarry lakes, settling ponds, and reservoirs, behave differently enough that treating them the same way during screening wastes weeks. Here's what each one brings to the table.
Quarry lakes: stable depth, murky ownership
Flooded quarries get overlooked in floating PV siting, which is a mistake. Once mining stops and the pit fills, the water level tends to stabilize fast, because there's no active drawdown for irrigation or municipal supply pulling it around. Depth is usually generous too, which matters less for the float system itself but a lot for mooring and anchor design.
What slows a quarry lake project down is the land around it, not the water itself. Quarry lakes frequently sit on land with layered ownership, a mining company that retained mineral rights, a reclamation trust, a local parks department that inherited the site. Shoreline access can be blocked by fencing left over from the operational quarry or by slopes too steep for equipment. None of that shows up on a satellite pass unless you're specifically scoring shoreline access alongside surface area, which is the part most manual screening skips because it takes a site visit to confirm.
Settling ponds and industrial ponds: steady but small
Settling ponds, tailings ponds, and other industrial retention basins get pitched a lot because they're already fenced, already permitted for industrial use, and usually sit next to a facility with load to serve on-site. That combination makes the interconnection story easy, which is why these show up early in a developer's shortlist.
Suitability on the water side is mixed. Some settling ponds hold a nearly constant level because they're part of a closed process loop. Others swing hard with seasonal discharge, batch dewatering, or sludge removal schedules, and a pond that drops two meters every quarter isn't going to hold an anchored float system without redesigning the mooring every few months. Surface area is usually the limiting factor here too. A lot of industrial ponds are a few hectares at most, which caps the project size regardless of how good the rest of the site looks.
Reservoirs: the default, not always the winner
Reservoirs get the most attention because they're the biggest and the best documented, at least on paper. Water utilities already track level data, shoreline easements are usually mapped, and the surface area is big enough to make a meaningful project. That's also exactly why reservoirs get oversubscribed. Every developer in the region is looking at the same handful of utility-owned lakes.
The level stability question cuts both ways on reservoirs. A reservoir built for flood control draws down hard in wet season by design, which is the opposite of what a floating array wants. A reservoir built for water supply with a stable minimum pool is a much better bet, but you won't know which kind you're looking at until you pull the operating records, and those aren't always public or current.
Running all three side by side
The honest version of this comparison is that none of the three types wins outright. Quarry lakes bring stability and depth but questionable access. Settling ponds bring easy interconnection but limited size and variable levels. Reservoirs bring scale and documentation but heavy competition and level profiles that depend entirely on how the reservoir is operated.
That's the actual argument for screening surface area, level stability, shading, and shoreline access together across every candidate water body in a region, instead of pulling level records one reservoir at a time and hoping the shoreline photos from five years ago are still accurate. Floating Solar Screening does exactly that, ranking quarry lakes, settling ponds, and reservoirs against each other from the same imagery pass so a project development team can see which water bodies are worth a site visit before spending one on them.
If you're building a shortlist across a region instead of chasing one reservoir at a time, that's the gap this is built to close.